Exercise generally falls into one of two categories—aerobic or anaerobic—and if your goal is simply to improve your physical fitness, you could probably get by for a while without ever knowing the difference. “Whether you’re training for aesthetic improvements, a specific activity or sport, or health-protective benefits, they’re both effective,” says Luke Carlson, founder and CEO of Discover Strength.
But as your goals begin to narrow, you’re going to want to understand the difference between aerobic and anaerobic exercise. Because, at a certain point, one will become significantly more valuable to you than the other. “You shouldn’t necessarily be doing 50-50, and it depends on your specific fitness goals,” says Irvin Sulapas, MD, a sports medicine physician at Houston Methodist. “Both are important, but you have to look at your goals.”
Here are the most important differences (and similarities) between aerobic and anaerobic exercise, according to experts, along with their advice for how to use both in your training.
Aerobic vs. anaerobic exercise
The difference between aerobic and anaerobic exercise is not so much about what you do but rather how you do it. For example, running can be aerobic, but it can also be anaerobic. The same goes for lifting weights. What differentiates an aerobic activity from an anaerobic one is the intensity, which in turn determines which energy pathway—aerobic or anaerobic—your body uses to sustain it.
Aerobic exercise, like running, swimming, or rowing at a moderate intensity, relies on oxygen. Anaerobic exercise, on the other hand—short, high-effort bursts, like sprinting or lifting heavy—is fueled by glycogen stored in the muscles. “With aerobic exercise, you’re working at a moderate intensity for longer periods of time, whereas anaerobic exercise is usually done at a high intensity for a much shorter duration,” says Dr. Sulapas.
While aerobic and anaerobic exercise rely on completely different energy pathways, the two are not mutually exclusive. It is possible to do a mostly aerobic or anaerobic workout—like a light jog or bench-pressing your one-rep max, respectively—however, more often than not, they work simultaneously. “Playing a game of volleyball or tennis is both aerobic and anaerobic,” says Carlson. Similarly, a HIIT workout might tax your anaerobic system for intense efforts and your aerobic system for overall endurance and recovery between intervals.
You should do both (but more of the one that supports your goals)
Aerobic and anaerobic exercise are both essential to improving your overall fitness, regardless of whether you’re a distance runner or a powerlifter. “I call it the yin and yang of exercise,” says Dr. Sulapas. “Aerobic exercise helps improve your cardiovascular fitness, your lung capacity, and your endurance, while anaerobic exercise builds up your strength, power, and muscle mass.”
The benefits of these two kinds of fitness also feed into one another. “If you don’t have strong muscles, you’re going to fatigue more quickly when you’re trying to do your aerobic exercises; similarly, you need aerobic fitness in order to up your intensity,” Dr. Sulapas says. “Long-distance runners, for example, should try to do some sort of anaerobic strength training about twice a week. And people who are concentrating more on strength building should routinely be doing some form of cardio to keep their endurance up for their heavy lifts.”
That’s not to say your training should be split 50-50 down the middle. If you’re gearing up for a half marathon, your training should be primarily aerobic. Conversely, if your goal is a bigger squat, anaerobic strength training should make up the bulk of your sessions. “Choose to prioritize aerobic or anaerobic exercise based on your activity or sport,” says Carlson. “Marathon running is 99.9 percent aerobic, so to prepare for it, you should do aerobic training. Football, meanwhile, is almost 100 percent anaerobic, so your training for that would be almost entirely anaerobic. We should always think about what it is that we are training for.”